Personally I'd rather see Stargirl than Supergirl if we're talking blonde teen superhero girls; more interesting character and powers IMO. Plus you don't have the whole "Oh, it's female Superman" thing. And I could see Robb (to use one of the OP's examples) working a lot better for Star than Kara.
Dusty Ayres wrote:
Adrianne Palicki played the fake Kara from Smallville
's S4 finale, and could still be a very solid choice, imo...
Sorry, but as beautiful as she is, I don't want anybody from Smallville
in any future Superman or Supergirl movie.
If it helps, she's better known (or at least should be better known) for her work on Friday Night Lights.